1) Field of the Invention
This invention relates in general to the remote release of a clamping force, such as to secure payloads in spacecraft during space launch and to then release the payloads for deployment.
2) Description of the Related Art
In space vehicle it is usual to secure payloads during one part of the mission and to separate payload components after a particular phase of the mission is completed. Explosive bolts are typically used to separate stages during launch. Explosive bolts actuate quickly, usually in milliseconds, to achieve simultaneity of release. Other types of separation devices are preferred for releasing payloads or for freeing subsystems such as shutters or photovoltaic arrays after low gravity is achieved. Non explosive release devices, such as disclosed in U.S. Pat. No. 5,119,555 to A. David Johnson et. al., impart less mechanical shock to the system and have advantages of testing subsystems prior to launch so that the same actuator used for testing may be flown on a mission.
A special case is one in which it is not desired to separate the components completely but to change the fastening so that the components can move a limited amount relative to each other while still maintaining a secure mechanical coupling. In this case it is convenient to change the length of one component of the clamping mechanism so that tension is released. The present invention provides a new and safe way of achieving such a release.